Abstract

We investigated whether sexual activity was associated with reproductive function in the BioCycle Study, a prospective cohort study that followed 259 regularly menstruating women aged 18 to 44years for one (n=9) or two (n=250) menstrual cycles in 2005-2007. Women were not attempting pregnancy nor using hormonal contraceptives. History of ever having been sexually active was assessed at baseline and frequency of sexual activity, defined as vaginal-penile intercourse, was self-reported daily throughout the study. Serum concentrations of estradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone, and testosterone were measured up to 8times/cycle. Sporadic anovulation was identified using peak progesterone concentration. Linear mixed models were used to estimate associations between sexual activity and reproductive hormone concentrations and generalized linear models were used to estimate associations with sporadic anovulation. Models were adjusted for age, race, body mass index, perceived stress, and alcohol consumption and accounted for repeated measures within women. Elevated concentrations of estrogen (+14.6%, P<.01), luteal progesterone (+41.0%, P<.01) and mid-cycle LH (+23.4%, P<.01), but not FSH (P=.33) or testosterone (P=.37), were observed in sexually active women compared with sexually inactive women (no prior and no study-period sexual activity); sexually active women had lower odds of sporadic anovulation (adjusted odds ratio=0.34, 95% confidence interval: 0.16-0.73). Among sexually active women, frequency of sexual activity was not associated with hormones or sporadic anovulation (all P>.23). Findings from our study suggest that ever having been sexually active is associated with improved reproductive function, even after controlling for factors such as age.

Average daily sexual intercourse relative to day of expected ovulation among women sexually active during the study (n= 135)P<.001 for overall variation in sexual intercourse across the menstrual cycle. Mixed model analyses took into account repeated measures from the same woman.P<.05 for the following pairwise comparisons used the Tukey method to account for multiple comparisons: days -6, -4 and 1 were each different from day -13; day -2 was different from days -11, -12, -13 and -14; day 0 was different from days -14 and -12.Average daily sexual intercourse during Mid-Cycle (19.0%) was significantly higher than the frequency of intercourse during Early Cycle (12.1%, P<.01), but not different from that during the Late Cycle (16.9%, P=.12).